120 
to be trusted as a test of geological age. Echinoderms, which 
are the principal fossils recognisable, have been collected from 
the Polyzoal rock, chiefly on the north side of Spring Creek, 
where it is typically developed, and prove to be the same as 
those from the rock face at Fishermen’s Steps. In addition, a 
few brachiopods, polyzoa, fragments of bivalves, &c., have been 
extracted from the same rugged rocks, but no species unrepre- 
sented in the accompanying strata have so far been noticed. On 
paleontological grounds, therefore, its separation from the adjoin- 
ing Echinoderm rock does not seem feasible. 
It is well known that the molluscan beds of Spring Creek, 
Curlewis, Mitchell River, Muddy Creek, &c., though agreeing in 
broad general characters, exhibit in each case certain faunal 
peculiarities, and when the polyzoal rocks accompanying them 
respectively are critically examined and compared, which is only 
partially done at present, considerable variation in their fossil 
contents will, no doubt, also be shown. For Muddy Creek and 
Spring Creek this can be already asserted—in fact, the polyzoal 
rock of Muddy Creek and the Grange Burn might with almost 
equal propriety be styled nummulitic limestone, from the 
abundance of Vummulites variolaria contained in it.* 
Attention has at various times been drawn to the probability 
that minor zones exist in the respective Eocene deposits of Vic 
toria. From the various observations recorded, it appears futile 
to seek them in any supposed undeviating sequence of the mol- 
luscan beds and their accompanying polyzoal rocks, the presence 
of one or the other in particular areas being probably dependent 
on bathymetrical conditions, but in the shell beds themselves, 
with their extremely rich fauna, the problem may possibly be 
attacked with greater chance of success. At Muddy Creek some 
work has been done in this direction, though, so far, with 
indefinite results ; but from the great height of the exposure at 
Spring Creek, fully 209 feet, a good opportunity is afforded for 
comparing the fauna of different levels. Along the whole sec- 
tion fallen blocks from the upper levels strew the beach, and 
hitherto collectors have mixed indiscriminately the fossils yielded 
by them with those gathered in situ from the lower part of the 
cliffs, the theory being that the fauna was practically indivisible. 
When collecting at the Fishermen’s Steps, the most character- 
istic shell obtained was Crassatella Hallii, which is very abun- 
dant, though rare at lower levels. Other species, as Lote 
Roblini, Corbula ephamilla, Natica polita, &c., have not been 
previously recorded from the Spring Creek section, and we offer 
the suggestion that at this level, and above the echinoderm rock, 
«Trans. Aust. Assoc. Adv. Science, Melbourne Meeting, pp. 442, 443. 
